- a mature, fully grown person; adult.
Origin of grownup
First recorded in 1805–15; noun use of verb phrase grow up
- having reached the age of maturity.
- characteristic of or suitable for adults: grown-up behavior; grown-up fiction.
Origin of grown-up
First recorded in 1625–35; adj. use of verb phrase grow up
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for grownup
I was happy Dad had let me be a grownup with him for a little while.Almost Famous: A Father's Day Story
June 15, 2014
If you think it is wrong, then act like a grownup and wait until you can buy it legally.Why Are Cable Companies Forcing People to Turn to Piracy?
November 28, 2012
And with a fine dose of ribbon embroidery and a bit of sparkle, grunge was dressed up enough for a grownup.Raf’s Ready-to-Wear Debut at Dior
September 28, 2012
They were not ostentatious as much as they were happy—in a grownup, made-peace-with-it-all way.Gucci by Sunlight
September 19, 2012
It seemed like the highest sophistication—good, grownup humor—yet still not boring for a 15-year-old girl.Diablo Cody on How Nora Ephron Blazed a Trail for Female Filmmakers
June 28, 2012
This was too big a thing, and too private, to tell a grownup.
The grownup straightened away from the fence, preparing to walk off.
His mother, his sister Margaret, and their grownup friends had finished their tea and were approaching from the house.Penrod
Onward and still onward to a glorious end, left entirely to myself and entrusted with an important task like a grownup person!The Bride of the Nile, Complete
He remembered Blanche Seymour as a passionate dancer still when he began to go to grownup parties.Aurora the Magnificent
- having reached maturity; adult
- suitable for or characteristic of an adult
- an adult
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012